My doctors told me to just stop the fently patch 50mg. I was on it for four weeks. I suffered like I never did in my life, chills that were pain, sweats at the same time. It took me 48 hrs. Then my doctors told me to just stop the Vicodin liquid i was taking for 6 weeks. Again I went through the same thing. It has been 3 days and today is the first day since Sunday that I feel somewhat normal.
Don't know if that helps or not, but it's my story.
I am almost 3 weeks out.

Age 57 at dx on 3/30/2009 by Dentist
SCC of R tonsil S2 Poorly Differentiated - 2.5 cm
Rad - IMRT 5x a wk for 8 wks starting 5/4/2009
No Chemo
Last Rad treatment was 6/26/2009.
Two years down as of 3/30/2011!
God bless all affected by this monster called cancer!